Lightheaded debuff applies Stun resistance

Blue Mage skill "Peripheral Synthesis" applies the Lightheaded debuff to enemies, which appears to share the same acquired resistance timer with Stun.

Steps:

1. Target [monster A] with Peripheral Synthesis, applying Lightheaded for 5 seconds.
2. Wait 5 seconds for Lightheaded debuff to expire.
3. Attack [monster A] again with Peripheral Synthesis, with the expected result of Lightheaded debuff time is halved to 2 seconds
4. Wait 2 seconds for Lightheaded debuff to expire
5. Attack [monster A] once more with Peripheral Synthesis, Lightheaded debuff will now apply for 1 second and expire. [monster A] will now Fully Resist the next application of Lightheaded.
6. Attack [monster A] with Faze.

Expectation: Faze should apply a 6 second Stun on [monster A] as this is the first Stun skill to have been used.
Observation: [monster A] will Fully Resist this first application of Stun.

Additional observation:
7. Attack [monster B] with Faze, applying Stun for 6 seconds.
8. Wait 6 seconds for Stun to expire
9. Repeat, until [monster B] Fully Resists application of Stun.
10. Attack [monster B] with Peripheral Synthesis

Expectation: This first use of Peripheral Synthesis on [monster B] should apply Lightheaded for 5 seconds
Observation: [monster B] will Fully Resist this first application of Lightheaded

I made a similar bug report before Endwalker came out. If you look at the Blue Mage Spellbook and filter the stun spells, Peripheral Synthesis is listed as a Stun. Prior to...6.1 I think, the spell was erroneously filtered under Slow. Thus, I assume this resistance behavior is intentional. However, I would like Lightheaded to not use Stun's resistance. At the very least, change the tooltip to mention Stun. :p

Good catch.

Presumably, since the skill needed some manner of resistance to function as intended, and devs did not wish to create a unique debuff resistance for this single skill, they simply chose another one that would work as well.
However, it becomes a particular problem in cases such as Masked Carnival #12, which requires Stun to prevent heavy damage. Players that use Peripheral Synthesis early in the fight of Act 2 will find that they are unable to Stun, and may be blocked from completion with no way of determining why Hydnora resists Stun despite the overview stating it should be vulnerable.